The invention relates to a hydraulic machine which can operate as a pump or motor and which is of the multicylinder drum type having a variable cylinder capacity.
A machine of this type has a rotatable shaft and a drive plate linked to piston and rod units received in the cylinders of the drum.
There are of course two kinds of hydraulic machine of this type: the so-called in-line machine in which the drum is rigidly secured axially to the shaft and the inclination of the drive plate relative to the shaft is variable; and the so-called split-shaft machine in which the drive plate is rigidly secured to the shaft and the drum can be inclined relative to the shaft.
This invention concerns a split-shaft machine of the second kind in which: the ends of the rods of the piston and rod units are pivotally received in spherical sockets provided in the surface of the drive plate facing the drum; each piston and rod unit is formed with a longitudinal liquid flow duct extending from the ends of the rod to the piston head; a liquid flow duct extends through the drive plate from the base of each of the spherical sockets to the opposite surface of the plate; the opposite surface of the plate bears on a distribution plate which is fixed in rotation, extends around the shaft and is pierced with at least one liquid flow orifice opposite which the ducts in the drive plate terminate; and stationary liquid flow conduit means is connected to each distribution plate orifice.
A machine of the foregoing construction obviates the need for the rotating hydraulic seal required at the fluid inlet and outlet of the drum because the latter is of variable inclination. Previously, in known machines of this kind, the fluid entered and left the drum via the inside of the drum-tilting pivots, so that a rotating seal had to be provided.
However, in the known split-shaft machines the force of the pistons is transferred to the bearings of the shaft which therefore have a limited working life and limited working pressures.
The present invention aims to provide a reduction in the forces applied to the shaft bearings and thereby the possibility of operating at higher pressures than has previously been possible.